Improvement in submarine harbor-defenses



UNITED STATES PATENT OFFICE.

JOHN S. GILBERT, OF NEW YORK, N. Y.

IMPROVEMENT IN SU BMARINE HARBOR-DEFENSES.

To all whom t may concern:

Beit known that I, J onN S. GILBERT, of New York, in the county andState of New York, have invented a new and useful Improvement inHarbor-Defense, which I term a Balance Submarine Harbor-Defense g and Ido hereby declare that the following is a full, clear, and exactdescription of the same, reference being had to the accompanying drawings, makin ga part of this specification, and to the letters of referencemarked thereon.

The object of my invention is to obstruct the entrance of a harbor tothe passage ofthe ships of an enemy. This has hitherto been essayed bymeans of sunken wrecks, which have been exceedingly objectionable onaccount of the obstruction they also offer to the passage of the water7which is certain to result in the formation of shoals and bars and achange of the channel, and ultimately in the destruction ofthe harbor.They are also difficult and expensive to remove when no longer required,and it has frequently happened that all attempts with the costlyappliances of diving-bells and submarine blasting have been insuicientto accomplish this purpose. Chains stretched across the entrance havealso been used, but it is necessary in wide spans to support them withbuoys or floats that can easily be destroyed by shot projected from adistance, causing the chain to drop and leaving the entrance open. Andchains of moderate length that are sufficiently strong to be strained ina line near the surface ofthe water and left unsupported offer butlittle resistance to the surge of a floating body propelled against it,on the same principle that the chain of a suspension-bridge is weakenedin proportion to the iiatness of the arc of the catenary employed.

My invention consists of a series of open crib-work frames or sectionsraised on legs from the bottom to permit a free passage of the current,and supporting a system of chains which are stretched between them insuch a manner that a vessel striking either against them or against theinclined ends of the frames will be deilected and clamped between thesections. Both the frames and the chains are teries.

fitted with iron tanks that are water and air tight, and of sufficientsize and buoyancy to oat the entire structure when its removal maybedesired. When these tanks are filled with water, the weight of thematerial of which they are constructed ballasts the sections steadily inposition.

The relative situation of the tanks and the center of gravity of thesections is established in such a manner that there isa constant balanceor restoring power preserved between the forces of buoyancy and gravitywhen the sections are being raised by forcing the water from the tankswith air or by pumping the water from them and allowing air to supplyits place. After the sections have been lifted a few feet to bring thechains to the surface, they may be detached and iioated separately away.

To enable others skilled in the art to which it appertains to make anduse my invention, I will proceed to describe its construction andoperation with reference to the drawings.

Figure l is a plan of a series of these frames or sections built andconnected according to my said invention. VOnly three sections have beenrepresented on the drawings, but as many of them may be used in asimilar manner as may be required by the extent of the harbor it isdesired to defend. Figs. 2 and 3 are respectively an end and a sideeleva-tion of the same.

The crib-work frames or sections a are sup= ported on the legs b, whichare built into the sides and extend to the top of the structures. Thefloor-beams c d e form spaces for the reception of the air-tight irontanks f, which are represented on the drawings as occupying the lowertier, but which may be placed, it'desired, in the upper tier of spacesin adjusting their buoyancy to the ballasting of the sections. Wherethese sections are necessarily constructed of large size to accommodatethem to a great depth of water, it is considered advisable to use tanksin both tiers, by which arrangement the lower ones will not only operateas ballast while filled with water and sub merged, but will furnishbuoyant power for floating the sections when required. The outer ends ofthe frames are formed angularly and are properly braced. The sides arealso furnished with diagonal braces for the reception of the angularstrain which would be occa sioned by a vessel striking on the end andfare pointed at the ends to diminish their resistance to the water. Theyare provided with suitable valves and connections for the reception ofmachinery, carried by an attendant vessel fitted for the purpose, forpumping air orv water to discharge the water within them Y after any ofthe various methods known to engineers and mechanics. These frames or sections may be constructed on shore and bolted and clamped together inthe ordinary manner with screw and key bolts, which canbe readilyremoved when it is desired to store or house ihe parts during such timeas they may not be required for the purposes of defense. They are madeentirely of straight timber, involve no skilled labor in theirconstruction, and can be built and placed in position under an emergencywith great facility and quickness. Being supported on legs that may bestrongly braced without oiler'ing any appreciable resistance to theWater, they are a sufticient distancev from the bottom to avoid anyscouring of the channel. The chains are fixed at the The tanks can beremoved for painting or repairs Without taking the sections apart, andthey may be used as reservoirs for the'storage of water and otherpurposes in barracks when no longer required by the necessities of warfor the office for which they were designed.

The crib-work may be of wood or iron, and may be ballasted, either inthe tanks or other- .wise, withv stone, iron, or any other material thatmay be convenient. Torpedoes may also be used in combination with thissystem of obstruction in such'a manner that they will be exploded undera vessel by its collision with the chains or front ends of the sections.

It is preferable for the convenience of lifting and transportation tovmake the sections in pairs; and it may be advantageouslto loop upthe'outer chains connecting the' sections with shackles that are weakerthan the links so that the shackles may be broken without breaking thechain, which will thus obtain sufficient scope to admit a vessel farenough to be resisted with the additional and comsbined force of thenext pair of chains.

